Ferroelectric capacitor and a method for manufacturing thereof

ABSTRACT

An object of the present invention is to provide a ferroelectric capacitor which shows excellent ferroelectricity. A silicon oxidation layer  4,  a lower electrode  12,  a ferroelectric layer  8  and an upper electrode  15  are formed on a silicon substrate  2.  The lower electrode  12  is made of palladium oxide. Also, the upper electrode  15  is made by palladium oxide, since palladium oxide prevents leakage of oxygen contained in the ferroelectric layer  8.  Thus, the ferroelectric capacitor of the present invention offers excellent ferroelectricity can be realized.

This is a continuation of international application Ser. No.PCT/JP96/01883, filed Jul. 5, 1996, the disclosure of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a ferroelectric capacitor, morespecifically, improvement of ferroelectricity and other characteristicsof the capacitor.

BACKGROUND ART

FIG. 10 shows a conventional ferroelectric capacitor. A siliconoxidation layer 4 is formed on a silicon substrate 2. A lower electrode6 made of platinum is provided thereon. A PZT (PbZr_(x) Ti_(1−x)O₃) film8 as a ferroelectric layer is formed on the lower electrode 6, and anupper electrode 10 made of platinum is provided thereon. Thus, theferroelectric capacitor is formed by the lower electrode 6, the PZT film8 and the upper electrode 10.

The reason to use platinum for the lower electrode 6 is as follows. ThePZT film 8 must be formed on a layer which can be oriented. Theferroelectricity of PZT is degraded if the PZT film can not be oriented,for example, when the PZT film is formed on an amorphous layer.Meanwhile, the lower electrode 6 must be formed under insulation fromthe silicon substrate 2. As such, the silicon oxidation layer 4 isformed on the silicon substrate 2. The silicon oxidation layer 4 is madeof amorphous material. In general, although a layer formed on anamorphous material becomes nonorientable, a layer made of platinum has acharacteristic of becoming orientable even when it is formed on theamorphous material. Therefore, platinum is used for forming the lowerelectrode because of the reason described in the above.

However, the conventional ferroelectric capacitor has following problemto be resolved.

The problems is degradation of ferroelectricity caused by frequentinversion of polarization, aging and leakage of oxygen from theferroelectric substance (PZT), since platinum has a tendency of allowingoxygen and Pb to pass through it. In other words, there is highprobability of leakage of oxygen and Pb contained in the ferroelectricsubstance through the columnar crystals of platinum shown in FIG. 11.The problem also arises in a capacitor using dielectric substance havinghigh dielectric constant.

DISCLOSURE OF THE PRESENT INVENTION

It is an object of the present invention to provide a ferroelectriccapacitor having less degradation of ferroelectricity caused by frequentinversion of polarization and aging or by a dielectric capacitormaintaining high dielectric constant, both of which resolve the problemdescribed in the above.

The word “capacitor” in the present invention defines structureproviding for electrodes on both sides of an insulator, also it is aconcept having the structure stated in the above regardless of using thestructure for electric storage.

In accordance with characteristic of the present invention, aferroelectric capacitor comprises:

a lower electrode having an oxidation layer made of any one of followinglayers, the layers at least including a layer made of WOx, a layer madeof TiOx, a layer made of TaOx, a layer made of IrO₂, a layer made ofPtO₂, a layer made of RuOx, a layer made of ReOx, a layer made of PdOxand a layer made of OsOx,

a dielectric layer composed by either of ferroelectric substance ordielectric substance having a high dielectric constant, the dielectriclayer being formed on the lower electrode, and

an upper electrode formed on the dielectric layer.

In other words, the lower electrode has at least one of followingoxidation layers such as the Wox layer, the TiOx layer, the TaOx layer,the IrO₂layer, the PtO₂ layer, the RuOx layer, the ReOx layer, the PdOxlayer and the OsOx layer. Therefore, it is possible to prevent leakageof oxygen from the dielectric layer as well as suppressing degradationof ferroelectricity caused by aging.

Also, in accordance with characteristic of the present invention, thelower electrode is composed by forming a conductive layer made of anyone of following layers, the layers at least including a layer made ofW, a layer made of Ti, a layer made of Ta, a layer made of Ir, a layermade of Pt, a layer made of Ru, a layer made of Re, a layer made of Pdand a layer made of Os on the oxidation layer, and a ferroelectric layeris formed on the conductive layer.

Further, in accordance with characteristic of the present invention, thelower electrode is formed on a silicon oxidation layer located on asubstrate, and wherein the lower electrode has a contact layer contactedto the silicon oxidation layer.

That is, one of the following conductive layer such as the W layer, theTi layer, the Ta layer, the Ir layer, the Pt layer, the Ru layer, the Relayer, the Pd layer and the layer Os layer is provided on the oxidationlayer. Then the dielectric layer is formed on the conductive layer.Therefore, leakage current can be decreased.

Still further, in accordance with characteristic of the presentinvention, a ferroelectric capacitor comprises:

a lower electrode,

a dielectric layer composed by either of ferroelectric substance ordielectric substance having a high dielectric constant, the dielectriclayer being formed on the lower electrode, and

an upper electrode formed on the dielectric layer and having anoxidation layer made of any one of following layers, the layers at leastincluding a layer made of WOx, a layer made of TiOx, a layer made ofTaOx, a layer made of IrO₂, a layer made of PtO₂, a layer made of RuOx,a layer made of ReOx, a layer made of PdOx and a layer made of OsOx.

In other words, the upper electrode has at least one of followingconductive layers such as the WOx layer, the TiOx layer, the TaOx layer,the IrO₂ layer, the PtO₂layer, the RuOx layer, the ReOx layer, the PdOxlayer and the OsOx layer. Therefore, it is possible to prevent leakageof oxygen from the dielectric layer as well as suppressing degradationof ferroelectricity caused by aging.

In accordance with characteristic of the present invention, the lowerelectrode is formed on a silicon oxidation layer located on a substrate,and wherein the lower electrode has a contact layer contacted to thesilicon oxidation layer.

Also, in accordance with characteristic of the present invention, aferroelectric capacitor comprises:

a lower electrode having an oxidation layer made of any one of followinglayers, the layers at least including a layer made of WOx, a layer madeof TiOx, a layer made of TaOx, a layer made of IrO₂, a layer made ofPtO₂, a layer made of RuOx, a layer made of ReOx, a layer made of PdOxand a layer made of OsOx,

a dielectric layer composed by either of ferroelectric substance ordielectric substance having a high dielectric constant, the dielectriclayer being formed on the lower electrode, and

an upper electrode having an oxidation layer made of any one offollowing layers, the layers at least including a layer made of WOx, alayer made of TiOx, a layer made of TaOx, a layer made of IrO₂, a layermade of PtO₂, a layer made of RuOx, a layer made of ReOx, a layer madeof PdOx and a layer made of OsOx.

That is, both of the upper electrode and the lower electrode have atleast one of following oxidation layers such as the WOx layer, the TiOxlayer, the TaOx layer, the IrO₂ layer, the PtO₂ layer, the layer RuOxlayer, the ReOx layer, the PdOx layer and the OsOx layer. Therefore, itis possible to prevent leakage of oxygen from the dielectric layer aswell as suppressing degradation of ferroelectricity caused by aging.

Further, in accordance with characteristic of the present invention, thelower electrode is composed by forming a conductive layer made of anyone of following layers, the layers at least includes a layer made of W,a layer made of Ti, a layer made of Ta, a layer made of Ir, a layer madeof Pt, a layer made of Ru, a layer made of Re, a layer made of Pd and alayer made of Os on the oxidation layer, and wherein a ferroelectriclayer is formed on the conductive layer.

Still further, in accordance with characteristic of the presentinvention, the lower electrode is formed on a silicon oxidation layerlocated on a substrate, and wherein the lower electrode has a contactlayer contacted to the silicon oxidation layer.

In other words, one of the following conductive layer such as the Wlayer, the Ti layer, the Ta layer, the Ir layer, the Pt layer, the Rulayer, the Re layer, the Pd layer and the Os layer is provided on theoxidation layer. Then the dielectric layer is formed on the conductivelayer. Therefore, leakage current can be decreased.

In accordance with the present invention, a ferroelectric capacitorwhich offers excellent ferroelectricity and high-dielectric property canbe provided.

In accordance with characteristic of the present invention, a method formanufacturing a ferroelectric capacitor comprises steps of:

forming any one of the following oxidation layers including a layer madeof WOx, a layer made of TiOx, a layer made of TaOx, a layer made ofIrO₂, a layer made of PtO₂, a layer made of RuOx, a layer made of ReOx,a layer made of PdOx and a layer made of OsOx on a substrate as a lowerelectrode by a sputtering method,

forming either of a ferroelectric film or a dielectric layer having ahigh dielectric constant on the lower electrode as a dielectric layer,and

forming an upper electrode on the dielectric layer.

Also, in accordance with characteristic of the present invention, amethod for manufacturing a ferroelectric capacitor comprises steps of:

forming any one of the following layers including a layer made of alayer made of W, a layer made of Ti, a layer made of Ta, a layer made ofIr, a layer made of Pt, a layer made of Ru, a layer made of Re, a layermade of Pd and a layer made of Os on a substrate as a base layer by asputtering method,

oxidizing a surface of the base layer,

forming either a ferroelectric film or a dielectric layer having a highdielectric constant on the base layer as a dielectric layer, a surfaceof the base layer being oxidized, and

forming an upper electrode on the dielectric layer.

Further, in accordance with characteristic of the present invention, amethod for manufacturing a ferroelectric capacitor comprises steps of:

forming either a ferroelectric film or a dielectric layer having a highdielectric constant on a lower electrode as a dielectric layer, and

forming any one of the following oxidation layers including a layer madeof WOx, a layer made of TiOx, a layer made of TaOx, a layer made ofIrO₂, a layer made of PtO₂, a layer made of RuOx, a layer made of ReOx,a layer made of PdOx and a layer made of OsOx on the dielectric layer asan upper electrode by a sputtering method.

Still further, in accordance with characteristic of the presentinvention a method for manufacturing a ferroelectric capacitor comprisessteps of:

forming a lower electrode on a substrate,

forming either a ferroelectric film or a dielectric layer having a highdielectric constant on the lower electrode as a dielectric layer,

forming any one of the following layers including a layer made of alayer made of W, a layer made of Ti, a layer made of Ta, a layer made ofIr, a layer made of Pt, a layer made of Ru, a layer made of Re, a layermade of Pd and a layer made of Os on the dielectric layer as a baselayer by a sputtering method, and

oxidizing a surface of the base layer.

In accordance with characteristic of the present invention, a method formanufacturing a ferroelectric capacitor comprises steps of:

forming any one of the following layers including a layer made of alayer made of W, a layer made of Ti, a layer made of Ta, a layer made ofIr, a layer made of Pt, a layer made of Ru, a layer made of Re, a layermade of Pd and a layer made of Os on a substrate as a base layer by asputtering method,

forming any one of the following layers including a layer made of alayer made of W, a layer made of Ti, a layer made of Ta, a layer made ofIr, a layer made of Pt, a layer made of Ru, a layer made of Re, a layermade of Pd and a layer made of Os on a surface of the base layer as aconductive layer,

oxidizing the conductive layer, a thin conductive layer being formed ona surface of the conductive layer,

step for forming either of a ferroelectric film or a dielectric layerhaving a high dielectric constant on the conductive layer as adielectric layer, the conductive layer being oxidized, and

forming an upper electrode on the dielectric layer.

Also, in accordance with characteristic of the present invention thestep of oxidization is carried out within the step for forming thedielectric layer.

While the novel features of the invention are set forth in a generalfashion, both as to organization and content, it will be betterunderstood and appreciated, along with other objections and featuresthereof, from the following detailed description taken in conjunctionwith the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing structure of a ferroelectric capacitor in anembodiment of the present invention.

FIG. 2 is a diagram showing a nonvolatile memory using a ferroelectriccapacitor 22.

FIG. 3A, FIG. 3B, FIG. 3C and FIG. 3D are flow charts showingmanufacturing processes of the ferroelectric capacitor.

FIG. 4 is a view showing structure of the ferroelectric capacitor when acontact layer 30 is provided.

FIG. 5 is a view showing structure of the ferroelectric capacitor when adielectric layer 90 having high dielectric constant is provided.

FIG. 6 is a view showing structure of a ferroelectric capacitor inanother embodiment of the present invention.

FIG. 7 is a view describing a mechanism that illustrates how thepalladium oxidation layer prevents leakage of oxygen from theferroelectric film.

FIG. 8A, FIG. 8B, FIG. 8C and FIG. 8D are flow charts showingmanufacturing processes of the ferroelectric capacitor shown in FIG. 1.

FIGS. 9A and 9B are views which show another embodiment of the presentinvention that caries out oxidization of palladium after forming a thinplatinum layer.

FIG. 10 is a view showing structure of the ferroelectric capacitor inthe prior art.

FIG. 11 is a view showing leakage of oxygen through the lower electrode6 made of platinum.

THE BEST MODE OF PREFERRED EMBODIMENT TO CARRY OUT THE PRESENT INVENTION

FIG. 1 shows the structure of a ferroelectric capacitor fabricated by anembodiment of the present invention. In the ferroelectric capacitor, asilicon oxidation layer 4, a lower electrode 12, a ferroelectric film(ferroelectric layer) 8 and an upper electrode 15 are formed on asilicon substrate 2. The lower electrode 12 is made of palladium oxide(PdOx), and the upper electrode 15 is also formed of palladium oxide(PdOx).

As shown in FIG. 11 which illustrates the conventional ferroelectriccapacitor, oxygen contained in the ferroelectric film 8 passes throughthe platinum layer having columnar crystals. Palladium oxide is used forthe lower electrode 12 in this embodiment of the present invention.Since the palladium oxide layer 12 does not have columnar crystals, itis hard for the oxygen to pass through it. As such, shortage of oxygenin the ferroelectric film 8 can be prevented. Shortage of oxygen canalso be prevented by the upper electrode 15 which does not have columnarcrystals. Thus, ferroelectricity of the ferroelectric film 8 isimproved. Remarkable improvement of ferroelectricity degradation causedby use of remnant polarization Pr is observed when either of the upperelectrode 15 or the lower electrode 12 is made of palladium oxide incomparison with when either one of the electrodes is composed byplatinum.

Since both of the lower electrode 12 and the upper electrode 15 are madeof palladium oxide in the embodiment described in the above, theelectrodes made of palladium oxide ensures prevention of leakage ofoxygen and Pb. Certain prevention of leakage can be expected when eitherof the electrodes is made by palladium oxide.

The ferroelectric capacitor described in the above can be used for anonvolatile memory when it is combined with a transistor 24 as shown inFIG. 2.

FIG. 3A, FIG. 3B, FIG. 3C and FIG. 3D are flow charts showingmanufacturing processes of a ferroelectric capacitor in an embodiment ofthe present invention. A silicon oxidation layer 4 is formed by carryingout thermal oxidation of a surface of the silicon substrate 2 (FIG. 3A).In this embodiment, the silicon oxidation layer 4 is formed in athickness of 600 nm. A palladium oxide formed on the silicon oxide layer4 by a reactive sputtering method using palladium as a target is definedas the lower electrode 12 (FIG. 3B). The lower electrode 12 is formed ina thickness of 200 nm.

A PZT film is formed on the lower electrode 12 as the ferroelectric film8 by sol-gel method (FIG. 3C). A mixed solution of Pb(CH₃COO)₂·3H₂O,Zr(t-OC₄H₉)₄ and Ti(i-OC₃H₇)₄ is used as a starter. The mixed solutionis dried at a temperature of 150° C. (hereinafter indicated in celsius)after carrying out spin coating, then pre-baking is carried out at atemperature of 400° C. for 30 seconds under dried air atmosphere.Thermal treatment at a temperature over 700° C. is carried out under O₂atmosphere after carrying out the processes described in the above for 5times. Thus, the ferroelectric film 8 having a thickness of 250 nm isformed. In this embodiment, the PZT film is formed at a ratio of xequals to 0.52 in PbZr_(x)Ti_(1−x)O₃ (hereinafter the material isindicated as PZT (52·48)).

Further, a layer made of palladium oxide is formed on the ferroelectricfilm as the upper electrode 15 by a reactive sputtering method (FIG.3D). The upper electrode 15 is formed in a thickness of 200 nm. Thus,the ferroelectric capacitor is completed. Any one of WOx, TiOx, TaOx,IrO₂, PtO₂, ReOx, RuOx, OsOx can be used for the palladium oxide.

In case of forming a layer made of ferroelectric substance on one of theoxidation layers, orientation of the ferroelectric substance isdegraded. In order to maintain the orientation, the layer made offerroelectric substance can be formed on any of following conductivelayers: a layer made of W, a Ti layer, a layer made of Ta, an Ir layer,a layer made of Pt, a Ru layer, a layer made of Re and an Os layer orthe like.

Further, leakage of the ferroelectric substance can be decreased byproviding the conductive layer.

FIG. 4 shows structure of a ferroelectric capacitor fabricated byanother embodiment of the present invention. In this embodiment, a layermade of titanium (having a thickness of 5 nm) is provided between thelower electrode 12 and the silicon oxidation layer 4 as a contact layer30. In general, palladium oxide and silicon oxide do not contact tightlywith each other. Thus, there is a probability of degradation offerroelectricity caused by the partial delamination of a layerconsisting of an alloy of palladium oxide and silicon oxide. To resolvethe degradation, the titanium layer 30 which can be contacted with thesilicon oxide layer 4 tightly is provided in this embodiment, so thatthe ferroelectricity is improved. The titanium layer can be formed by asputtering method.

Although the titanium layer is used as the contact layer 30 in theembodiment described in the above, any other materials which improvecontact can be utilized. For instance, a layer made of platinum can beused for the contact layer.

Though, the PZT film is used as the ferroelectric film 8 in theembodiment described in the above, any other materials can be utilizedas long as the materials are ferroelectric oxide.

FIG. 5 shows the structure of a ferroelectric capacitor fabricated byanother embodiment of the present invention. A dielectric layer 90having high dielectric constant is used for the ferroelectric film 8 inthis embodiment. The lower electrode 12 made of palladium oxide isprovided on the silicon oxide layer 4, and a high dielectric thin filmmade of SrTiO₃, (Sr, Ba)TiO₃ having a perovskite structure is formedthereon as the dielectric layer 90. In this embodiment, ferroelectricityis improved in the same manner as in the embodiment using theferroelectric substance. In other words, it is clarified that theadvantages offered by using the ferroelectric layer can also be obtainedby utilizing the dielectric layer having high dielectric constant.

FIG. 6 shows the structure of a ferroelectric capacitor fabricated bystill another embodiment of the present invention. In this embodiment,the silicon oxidation layer 4, the lower electrode 12, the ferroelectricfilm (ferroelectric layer) 8 and the upper electrode 15 are provided onthe silicon substrate 2. The lower electrode 12 consists of a palladiumlayer and a palladium oxide layer formed thereon. Also, the upperelectrode 15 consists of a palladium layer 7 and a palladium oxide layer9 formed thereon.

FIG. 7 is an enlarged view of the vicinity of the lower electrode 12.Since the palladium oxide layer 11 has columnar crystals, the oxygencontained in the ferroelectric film 8 passes through the palladium oxidelayer 11. Another palladium oxide layer 13 is formed on the uppersurface of the palladium oxide layer 11 in this embodiment. As such, itis possible to prevent a shortage of oxygen contained in theferroelectric film 8 by forming the palladium oxide layer 13 asdescribed in the above. The upper electrode 15 obtains the sameadvantage which the lower electrode 12 offers as described in the above.

Since both of the palladium oxide layers are formed in the lowerelectrode 12 and the upper electrode 15 respectively in this embodiment,it is possible to obtain a ferroelectric capacitor having an excellentferroelectricity as well as having less influences of aging. Certainadvantage described in the above can be observed when either of thelower electrode 12 or the upper electrode 15 is formed by the structuredescribed in the above.

FIG. 8A, FIG. 8B, FIG. 8C and FIG. 8D are flow charts showingmanufacturing processes of the ferroelectric capacitor described in theabove. The silicon oxidation layer 4 is formed by carrying out thermaloxidation on a surface of the silicon substrate 2 (FIG. 8A). In thisembodiment, the silicon oxidation layer 4 is formed in a thickness of600 nm. The palladium oxide layer 11 is formed on the silicon oxidelayer 4 by utilizing palladium as a target (FIG. 8B). The palladiumoxide layer 13 is formed by carrying out a thermal treatment at atemperature of 800° C. for one minute under O₂ atmosphere. The palladiumlayer 11 and the palladium layer 13 thus formed are defined as the lowerelectrode 12. The lower electrode 12 is formed in a thickness of 200 nm.

A PZT film is formed on the lower electrode 12 as the ferroelectric film8 by sol-gel method (FIG. 8C). A mixed solution of Pb(CH₃COO)₂·3H₂O,Zr(t-OC₄H₉)₄ and Ti(i-OC₃H₇)₄ is used as a starter. The mixed solutionis dried at a temperature of 150° C. (hereinafter indicated in celsius)after carrying out spin coating, then pre-baking is carried out at atemperature of 400° C. for 30 seconds under dried air atmosphere.Thermal treatment at a temperature over 700° C. is carried out under O₂atmosphere after carrying out the processes described in the above for 5times. Thus, the ferroelectric film 8 having a thickness of 250 nm isformed. In this embodiment, the PZT film is formed at a ratio of xequals to 0.52 in PbZr_(x)Ti_(1−x)O₃ (hereinafter the material isindicated as PZT (52·48)).

Further, the palladium oxide 7 is formed on the ferroelectric film 8 bya sputtering method. Then, the palladium oxide layer 9 is formed on asurface of the palladium layer 7 by carrying out a thermal treatment ata temperature of 800° C. for one minute under O₂ atmosphere (FIG. 8D).The palladium layer 7 and the palladium oxide layer 9 thus formed aredefined as the upper electrode 15. The upper electrode 15 is formed in athickness of 200 nm. Thus, the ferroelectric capacitor is completed.

It is also preferable to form the contact layer 30 in the ferroelectriccapacitor as described in FIG. 4.

The process which oxidizes a surface of the palladium described in theabove can be applied not only to the ferroelectric film, but also to thedielectric layer having high dielectric constant described in the above,so that the same advantages can be expected.

As described in the above, though leakage of oxygen can be prevented byoxidizing the surface of the palladium layer, orientation of theferroelectric layer is degraded by formation of the palladium oxide onits surface. This problem can be resolved by formation of any offollowing conductive layers on the palladium oxide layer 13, such as thelayer made of W, the Ti layer, the layer made of Ta, the Ir layer, thelayer made of Pt, the layer made of Ru, the layer made of Re and the Oslayer or the like as already has been mentioned. The problem can also beresolved by forming the lower electrode as is now described.

At first, a platinum layer 80 (thin film conductive substance) is formedvery thinly on the palladium layer 11 having an Ir layer as shown inFIGS. 9A and 9B. The platinum layer 80 is formed in a thickness of 30 nmas shown in FIG. 9A. Thereafter, a thermal treatment is carried out, asshown in FIG. 9B. The platinum layer is not oxidized because theplatinum layer 80 exposed on the surface does not react to oxygen. Also,leakage of oxygen is shut out by the formation of palladium oxide and/orindium oxide (IrO₂) between the crystals of the palladium layer 11located under the platinum layer 80 as a result of the oxidization ofthe crystals, because the platinum layer 80 is formed thinly. As such,the lower electrode 12 which can shut out leakage of oxygen whilemaintaining good orientation can be formed.

The palladium layer 11 formed on the thin platinum layer 80 and thenoxidized can also be used as the lower electrode 12 by itself. Thepalladium layer 11 can be used as the conductive layer having goodorientation in the embodiment of improving orientation by providing aconductive layer (a palladium layer, a platinum layer and the like)having good orientation on the palladium layer formed by sputtering.

Also, all of the embodiments described in the above can be applied notonly to the ferroelectric capacitor using the ferroelectric film butalso to the capacitor using the dielectric layer having high dielectricconstant. Exactly the same advantage offered by applying the presentinvention to the ferroelectric film can be obtained when the presentinvention is applied to the dielectric layer having high dielectricconstant.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than limitation and that changes within the purviewof the appended claims may be made without departing from the true scopeand spirit of the invention in its broader aspects.

What is claimed is:
 1. A method for manufacturing a ferroelectriccapacitor comprising the steps of: forming a layer of columnar crystalscomprising a metal selected from the group consisting of W, Ti, Ta, Ir,Pt, Ru, Re, Pd, and Os on a substrate as a base layer by a sputteringmethod, oxidizing the crystals at the surface of the base layer to forma metal oxide between the columnar crystals of the layer tosubstantially prevent a penetration of oxygen through the layer, forminga conductive layer on the oxidized surface of the base layer, forming atleast one of a ferroelectric film and a dielectric layer having aperovskite structure on the conductive layer as an insulative layer, andforming an upper electrode on the insulative layer, wherein theconductive layer substantially prevents degradation of the orientationof the insulative layer.
 2. A method for manufacturing a ferroelectriccapacitor comprising the steps of: oxidizing columnar crystals at asurface of a lower electrode to form a metal oxide between the columnarcrystals of the lower electrode to substantially prevent penetration ofoxygen through the lower electrode; forming a conductive layer on theoxidized surface of the lower electrode; forming at least one of aferroelectric film and a dielectric layer having a perovskite structureon the conductive layer as an insulative layer, and forming a layerselected from the group consisting of WO_(x), TiO_(x), TaO_(x), IrO_(x),PtO_(x), RuO_(x), ReO_(x), PdO_(x), and OsO_(x) on the insulative layeras an upper electrode by a sputtering method, wherein the conductivelayer substantially prevents degradation of the orientation of theinsulative layer.
 3. A method for manufacturing a ferroelectriccapacitor comprising the steps of: forming a lower electrode made of amaterial of columnar crystals on a substrate, forming a conductive layeron the surface of the lower electrode, wherein the conductive layercomprises a material selected from the group consisting of W, Ti, Ta,Ir, Pt, Ru, Re, Pd, and Os, oxidizing the columnar crystals at thesurface of the lower electrode to form a metal oxide between thecolumnar crystals of the lower electrode to substantially prevent apenetration of oxygen through the lower electrode, forming at least oneof a ferroelectric film and a dielectric layer having a perovskitestructure on the conductive layer as an insulative layer, and forming anupper electrode on the insulative layer by a sputtering method so as tocover the surface of the insulative layer, wherein the conductive layersubstantially prevents degradation of orientation of the insulativelayer.
 4. A method for manufacturing a ferroelectric capacitorcomprising the steps of: forming a first layer of a material selectedfrom the group consisting of W, Ti, Ta, Ir, Pt, Ru, Re, Pd, and Os on asubstrate by a sputtering method, forming a second layer made ofcolumnar crystals comprising a material selected from the groupconsisting of W, Ti, Ta, Ir, Pt, Ru, Re, Pd, and Os on a surface of thefirst layer, oxidizing the surface of the second layer to form a metaloxide between the surface columnar crystals of the second layer tosubstantially prevent a penetration of oxygen through the second layer,forming a conductive layer on the oxidized surface of the second layer,forming at least one of a ferroelectric film and a dielectric layerhaving a perovskite structure on the conductive layer as an insulativelayer, and forming an upper electrode on the insulative layer, whereinthe conductive layer substantially prevents degradation of orientationof the insulative layer.
 5. A method for manufacturing a ferroelectriccapacitor comprising the steps of: forming a silicon oxidation layer ona silicon substrate by thermal oxidation; forming a first palladiumoxide layer on the silicon oxidation layer by reactive sputtering;forming a dielectric layer on the palladium oxide layer; and forming asecond palladium oxide layer on the dielectric layer by reactivesputtering; wherein the first palladium oxide layer serves as a lowerelectrode for the capacitor, and the second palladium oxide layer servesas an upper electrode for the capacitor.
 6. The method of claim 5wherein the dielectric layer is a layer selected from the groupconsisting of a SrTiO₃ layer and a (Sr, Ba)TiO₃ layer.
 7. A method formanufacturing a ferroelectric capacitor comprising the steps of: forminga silicon oxidation layer on a silicon substrate by thermal oxidation;forming a lower electrode on the silicon oxidation layer by reactivesputtering; forming a ferroelectric film on the lower electrode; andforming an upper electrode on the ferroelectric film by reactivesputtering; wherein the lower and upper electrodes are formed of amaterial selected from the group consisting of WOx, TiOx, TaOx, IrO₂,PtO₂, ReOx, RuOx and OsOx.
 8. A method for manufacturing a ferroelectriccapacitor comprising the steps of: forming a silicon oxidation layer ona silicon substrate by thermal oxidation; forming a first palladiumoxide layer on the silicon oxidation layer by reactive sputtering;forming a ferroelectric film on the palladium oxide layer; and forming asecond palladium oxide layer on the ferroelectric film by reactivesputtering; wherein the first palladium oxide layer serves as a lowerelectrode for the ferroelectric capacitor, and the second palladiumoxide layer serves as an upper electrode for the ferroelectriccapacitor.
 9. The method of claim 8, further comprising the step ofproviding a titanium contact layer between the lower electrode and thesilicon oxidation layer by sputtering.
 10. The method of claim 9 whereinthe contact layer has a thickness of approximately 5 nm.
 11. The methodof claim 8, further comprising the step of providing a platinum contactlayer between the lower electrode and the silicon oxidation layer bysputtering.
 12. The method of claim 8 wherein the ferroelectric film isa PbZr_(x)Ti_(1−x)O₃ (PZT) film.
 13. The method of claim 8 wherein theferroelectric film is a Bi₄Ti₃O₁₂ film.
 14. The method of claim 8,wherein the first palladium oxide layer is formed from a surface of afirst palladium layer, which is made of columnar crystals, by thermaltreatment; wherein the second palladium oxide layer is formed from asurface of a second palladium layer, which is made of columnar crystals,by thermal treatment; wherein the first palladium layer and the firstpalladium oxide layer serve as the lower electrode for the ferroelectriccapacitor, and the second palladium layer and the second palladium oxidelayer serve as the upper electrode.
 15. The method of claim 14, furthercomprising the steps of: forming a platinum layer on the first palladiumlayer; and carrying out a thermal treatment resulting in the formationof the first palladium oxide layer from the crystals at the surface ofthe first palladium layer by forming palladium oxide between thecolumnar crystals of the first palladium layer located under theplatinum layer, to thereby prevent leakage of oxygen through the lowerelectrode; wherein the platinum layer is not oxidized.
 16. The method ofclaim 15, further comprising the step of providing a titanium contactlayer between the lower electrode and the silicon oxidation layer. 17.The method of claim 15, further comprising the step of providing aplatinum contact layer between the lower electrode and the siliconoxidation layer.
 18. The method of claim 15 wherein the ferroelectricfilm is a PbZr_(x)Ti_(1−x)O₃ (PZT) film.
 19. The method of claim 15wherein the ferroelectric film is a Bi₄Ti₃O₁₂ film.
 20. The method ofclaim 15 wherein the platinum layer has a thickness of approximately 30nm.
 21. The method of claim 14, further comprising the steps of: formingan iridium layer on the first palladium layer; and carrying out athermal treatment resulting in the formation of the first palladiumoxide layer from some of the crystals at the surface of the firstpalladium layer by forming a palladium oxide between the columnarcrystals of the first palladium layer located under the iridium layer,thereby preventing leakage of oxygen though the lower electrode; whereinthe iridum layer is not oxidized.
 22. The method of claim 14, furthercomprising the steps of: forming a conductive layer on the firstpalladium layer; and carrying out a thermal treatment resulting in theformation of the first palladium oxide layer from the crystals at thesurface of the first palladium layer by forming a palladium oxidebetween the columnar crystals of the first palladium layer located underthe conductive layer, thereby preventing leakage of oxygen though thelower electrode; wherein the conductive layer is not oxidized and iscomprised of a material selected from the group consisting of W, Ti, Ta,Ir, Pt, Ru, Re and Os.
 23. The method of claim 8 wherein the siliconoxidation layer has a thickness of approximately 600 nm.
 24. The methodof claim 8 wherein the lower electrode has a thickness of approximately200 nm.
 25. The method of claim 8 wherein the ferroelectric film has athickness of approximately 250 nm.
 26. The method of claim 8 wherein theupper electrode has a thickness of approximately 200 nm.